Exchange executives, long shielded from legal scrutiny in the U.S., have been put on notice that may be changing after federal regulators fined CBOE Holdings Inc. $6 million for unprecedented lapses in supervision.

OptionsXpress Inc., a unit of U.S. brokerage Charles Schwab Corp., and its former chief financial officer helped to facilitate sham transactions that violated U.S. securities laws, an administrative court ruled.

optionsXpress Inc., its former chief financial officer and an affiliated dealer were accused by U.S. regulators of violating securities laws by skirting registration requirements in order to avoid an audit.